Texas faces “dangerous” flood threat as tropical system approaches

Although the radar is somewhat quiet across most of Houston this morning, it won’t remain that way as atmospheric moisture levels rise.

Forecast models show scattered to widespread showers streaming into the region from the coast later this morning, and continuing through the afternoon.

Accumulations today may be 0.5 to 3 inches of rain, or so.

But really, today’s rain is just an appetizer for the main course, which is now over the Yucatan Peninsula and moving toward the western Gulf of Mexico. This tropical system, which the National Hurricane Center gives a 60 percent chance of developing into a tropical depression or storm, will prove a potent rainmaker for Texas regardless of how much it develops.

A Saturday morning satellite image of the tropical system that threatens Texas. (NOAA)

Forecast models now suggest the system will track toward the middle Texas coast, reaching the state some time on Tuesday, perhaps during the afternoon or evening hours.

The precise landfall location is somewhat immaterial for this system as we’re not particularly concerned about storm surge or wind, but rather rainfall and inland flooding. And right now it appears the storm will produce heavy rain across a very large area.

The GFS model offers an example of the kind of rain swath this storm could leave as it moves over Texas, Oklahoma and the central United States over the next five days.

GFS model five-day rainfall accumulation forecast. (Weather Bell)

Moreover, the GFS forecast may be conservative in terms of rainfall accumulations along the coast and for Texas counties immediately inland. This storm is bringing a lot of moisture. The European forecast model, for example, projects rainfall accumulations of 12 to 14 inches in some coastal Texas counties to the east of the storm as it comes ashore.

In recognition of this threat the Houston/Galveston office has said the entire metro area faces a “dangerous” flood threat on Monday and Tuesday, and that holds for the central Texas coast as well.

The bottom line is that all of central, southeast and east Texas face the possibility of heavy rains and major flooding from Monday through Wednesday as this system approaches the coast and then moves inland. It’s really not a matter of whether it will rain, but where the heaviest rain will fall and the inevitable flooding will occur.